The present invention relates generally to a liquid level sensor that senses the level of a fluid using a flexural vibration wave group or packet.
One method of detecting the level of a fluid involves the generation of an extensional order waves with an out of plane component that is propagated down the length of a rod. The out of plane component of the wave creates a motion that causes compressional waves in a fluid as the wave propagates down a rod immersed in the fluid. When the wave group contacts the end of the rod, it is reflected backwards towards a transducer. The transducer then analyzes the wave reflected by the end of the rod to determine if the rod is in a fluid. However, these sensors operate poorly in aerated fluids due the interaction of the fluid pressure waves and the bubbles produced in the aerated fluid. To minimize bubbles, many sensors of this type incorporate a baffle around the sensor to prevent bubbles in the fluid from interfering with the operation of the sensor. However, these baffles complicate the installation of the sensor, and also increase the installation costs of the device.
Accordingly, a need exists for a level sensing device that can directly detect the level of an aerated fluid without the use of a baffle or external device.